About Rationel Windows
Rationel is an international company which manufacturers and sells state-of-the-art windows and doors in Denmark and around the world. Every year they dispatch 350,000 windows and doors from our factories in modern and classic styles for both new build and refurbishment projects.
How it began
It all began in Sdr. Felding with a hard-working carpenter and an order for 31 barn windows. As a young apprentice in the 1930s, Richard R. Nielsen had craftsmanship in his soul. In those days everything was made by hand – in fact his boss did not even own a machine.
As a skilled craftsman, Richard R. Nielsen soon bought his own joinery workshop, where he continued this proud tradition. Then in 1954, he had his first order for 31 barn windows, which enabled him to invest in some modern machinery. Soon the workshop became a factory and Richard R. Nielsen built up a solid business based on consistently high standards of workmanship and quality.
High quality windows and doors
More than 60 years later Rationel employs 1,050 people in Denmark, England, Ireland and Poland. They continue to manufacture high quality windows and doors that are durable and designed to last.
They not only withstand wind and rain, and attempted break-ins, but the constant wear and tear of busy family life with young and teenage children repeatedly opening and closing windows and doors year after year. This is not just something that they talk about. “Durability is something that they test again and again from every conceivable angle,” says CEO Thomas Tvedergaard Larsen.
Continuous improvement
New windows and doors are an investment in the future. They must match the house style and energy requirements, whilst living up to homeowners’ expectations and lifestyle aspirations. That is why they are continually working to improve and make our products even better. they call this ‘Future Excellence’. The whole company takes part in ‘Future Excellence’. It is about enhancing efficiency, optimizing and making improvements in the workplace.
No project is too big or too small. Every year they launch over 100 projects, which focus on everything from the quality of our business practices though to staff morale and job satisfaction. they are continually reviewing our performance and whether they are meeting our deadlines, following our strategies and achieving our goals.
Strong corporate ownership
Rationel is part of DOVISTA Group, which consists of ten leading window manufacturers in Europe with a common mission to bring natural daylight, fresh air and a better environment into people’s everyday lives. DOVISTA is owned by VKR Holding whose companies employ approximately 13,500 people in more than 40 countries.
Care for climate and environment
They believe it is important to look after the climate and the environment. Our timber comes from FSC-certified forests in Stheyden, which they then treat with eco friendly products. they recycle waste glass, paint and aluminum and they heat our factories with recycled wood from our production processes. In other words, they produce windows and doors with a clear conscience.
At the same time a portion of our profits goes to the Villum Foundation, the main shareholder of VKR Holding, which owns Rationel. Arguably one of Denmark’s most discreet and wealthy environmentalists, the Foundation donates 15 million pounds to environmental and climate projects every year. Together with several other foundations associated with the VKR Group, it funds nonprofit scientific, cultural, artistic and social initiatives.
A trip around Rationel
With its modern production facilities and superior products, all of which comply with building regulations, Rationel is in the forefront of energy-efficient window and door manufacturing. Take a trip around Rationel Windows in this video.

